This invention relates generally to deformation imaging and more particularly to a deformation imaging system including an imaging member comprising a layer of a surface deformable material and a layer of elastomer material.
There is known in the deformation imaging art a class of imaging members which utilize surface deformable imaging materials such as thermoplastic resin materials. Such imaging members are used in deformation imaging methods such as Frost deformation imaging, relief deformation imaging and variations of Frost and relief deformation imaging wherein an optical screen is used to modulate the image information. Generally, in both Frost and relief deformation imaging, an imaging member comprising a layer of a suitable surface deformable material and including photoconductive insulating material, either in the form of a separate layer or incorporated in the surface deformable material layer, is electrostatically charged such as with a corona charging device, exposed to an imagewise pattern of activating electromagnetic radiation, (optionally charged a second time in the case of Frost deformation imaging) and then developed by softening the surface deformable material layer such as by heating. An imagewise deformation pattern corresponding to the image input is formed in the layer of surface deformable material and this image may be read out by projection either in transmission or reflection. Typically the images formed in Frost and relief deformation imaging members are permanent images, i.e., they will be retained indefinitely in the member. Also, both Frost and relief imaging members can typically be recycled many times, that is, old images may be erased such as by softening the surface deformable imaging material and new images recorded therein according to the well known methods. Because of these characteristics as well as other desirable properties, these imaging members are advantageous for use in many imaging applications.
However, Frost and relief deformation imaging members have not proved to be completely satisfactory when used in a recyclable mode. Typically, it has been found that each succeeding image recorded in these members is somewhat inferior in quality to its predecessor and the number of imaging cycles for which the members will provide acceptable results is limited. These characteristics may be attributable to residual memory effects in the surface deformable material which cause some memory of the previous images to be retained and to contamination of the deformable surface by the permanent accumulation of dust which is acquired during the charging step and permanently affixed during the subsequent softening of the material during development. It would be desirable to extend the recycling capability of imaging members which include a layer of a surface deformable material.
There is also known in the imaging art a broad class of imaging members which record optical images by an imagewise distribution of photogenerated voltages or currents acting upon a voltage or current-alterable recording medium. Typically, in these members, imagewise activating radiation incident on a photoconductor allows charge carriers to move in an electric field. These charge carriers interact with a voltage or current sensitive member which in turn modulates light. Sheridon has disclosed the Ruticon (derived from the Greek words "rutis" for wrinkle and "icon" for image) family of imaging members wherein a voltage-sensitive, light modulating recording medium comprises a deformable elastomer layer and the photoconductive material may be provided as a separate layer or incorporated in the elastomer layer. (For a detailed description of the Ruticon devices see IEEE Transactions on Electron Devices, September, 1972 and U.S. Pat. No. 3,716,359.) Various different embodiments for establishing an electric field across the elastomer layer are described. Generally, imaging is effected by establishing an electrical field across the elastomer layer and exposing the imaging members to an imagewise pattern of activating electromagnetic radiation. An imagewise deformation pattern corresponding to the image input information is formed in the layer of elastomer material and the image may be read out by projection such as with a Schlieren optical system. Ruticon imaging members are capable of providing excellent images over a great number of imaging cycles and are advantageous for use in many applications such as, for example, image intensification, etc. Moreover, these members may also be used for buffer storage of images since the images formed typically remain for some period of time after exposure is completed. This image storage capability is limited though, since the images typically erase because of various effects which cause the contrast potential across the elastomer layer to diminish or disappear. It would be desirable to extend the image storage time of imaging members which include a layer of elastomer material.